Riboflavin as a Mucosal Adjuvant for Nasal Influenza Vaccine

Area of Science:

• Immunology
• Vaccinology

Background:

• Intranasal immunization with whole inactivated virus (WIV) is crucial for influenza control.
• Developing effective mucosal adjuvants is essential to enhance nasal vaccine efficacy.

Purpose of the Study:

• To investigate the potential of riboflavin as a mucosal adjuvant for intranasal influenza vaccination.
• To evaluate the impact of riboflavin on immune responses and vaccine protection.

Main Methods:

• Mice were intranasally immunized with H1N1 WIV plus riboflavin.
• Assessed secretory IgA (sIgA) and serum IgG levels.
• Evaluated protection against lethal influenza challenge.
• Analyzed dendritic cell (DC) maturation and cytokine secretion.
• Investigated the role of the mitogen-activated protein kinase (MAPK) signaling pathway.

Main Results:

• Riboflavin significantly enhanced sIgA levels in the respiratory tract and upregulated serum IgG.
• A decreased IgG1/IgG2a ratio indicated a shift in cellular immunity.
• Riboflavin improved protection against a lethal influenza challenge.
• Riboflavin promoted DC phenotypic and functional maturation via MAPK signaling.

Conclusions:

• Riboflavin acts as a potent mucosal adjuvant for influenza WIV nasal vaccines.
• It enhances both humoral and cellular immunity, leading to improved vaccine efficacy.
• Riboflavin is a promising candidate for developing alternative mucosal adjuvants for influenza nasal vaccines.